1. Field of the Invention
The present invention relates to wireless identification tags, and more specifically, to systems and methods for coordinating data transmission from wireless identification tags.
2. Description of Related Art
Wireless identification tag technology utilizes wireless communication techniques to transfer data from a wireless identification tag, such as a radio frequency identification (RFID) tag or transponder, to a wireless identification reader. In an example, applications of RFID technology include affixing an RFID tag to an object for identifying and tracking the object. Additional example applications for RFID technology include tracking inventory, store items, assets, people, and the like. For example, an RFID tag may be affixed to food items, cars, computer equipment, books, and mobile phones.
In retail environments, such as grocery stores, RFID tags may be affixed to items for identifying the items during checkout and for tracking movement of the items throughout the store. One or more RFID read cells may be placed in the store for wirelessly signaling RFID tags within its communication range to activate. One difficulty can occur when an RFID read cell simultaneously activates multiple RFID tags. In this scenario, the RFID tags will simultaneously transmit their data to the RFID read cell. Such simultaneous transmission by the RFID tags can result in signaling collisions. Current collision avoidance techniques include halting data transmission and subsequently waiting for a random time period before again attempting to transmit data from an RFID tag. However, collisions may continue to occur later when two or more of the RFID tags transmit simultaneously. Further, as the number of RFID tags increase, the time needed to read data from all the RFID tags increases. In view of these difficulties, there is a need for improved RFID tag management systems and techniques.